Subaru Repair: P0400 Code, o2 sensors, pindle

Question
I keep receiving the P0400 code. I think this is a generic code for the EGR system but what do you suggest it could be. I removed the EgR valve and clean all of the carbon build up. I also checked to see if the pindle was freely moving while revving the engine and it is. I seem to get the Service Engine light at approximately 2200-2500 RPM's. I know this because I bought a scanner with live and freeze frame data. The car also seems to run very sluggish at low speeds especially when cold. It seems to bog down and takes a couple of seconds to accelerate. I changed the air filter, the fuel filter, the O2 sensors where also changed (they needed to be changed,they threw a code), and I also installed a new EGR valve solenoid. The bogging down/hesitation still exists when  cold. So I have 2 problems. The P0400 code and the bogging down/hesitation a low speeds when cold. The hesitation does not through a code though, only the P0400. Please help......
Thanks...Mike

Answer
If you can get me the year make and model, I think I can get you a pdf file from Subaru that will help you diagnose this one. Just be warned, next to an intermit misfire, this is one of the toughest to diag without switching parts. But, sounds like you are up to it. Try me at tuckerserv@naxs.net. Z